Chromosome-scale assembly and gene editing of Solanum americanum genome reveals the basis for thermotolerance and fruit anthocyanin composition.

Solanum americanum serves as a promising source of resistance genes against potato late blight and is considered as a leafy vegetable for complementary food and nutrition. The limited availability of high-quality genome assemblies and gene annotations has hindered the exploration and exploitation of stress-resistance genes in S. americanum. Here, we present a chromosome-level genome assembly of a thermotolerant S. americanum ecotype and identify a crucial heat-inducible transcription factor gene, SaHSF17, essential for heat tolerance. The CRISPR/Cas9 system-mediated knockout of SaHSF17 results in remarkably reduced thermotolerance in S. americanum, exhibiting a significant suppression of multiple HSP gene expressions under heat treatment. Furthermore, our transcriptome analysis and anthocyanin component investigation of fruits indicated that delphinidins are the major anthocyanins accumulated in the mature dark-purple fruits. The accumulation of delphinidins and other pigment components during fruit ripening in S. americanum coincides with the transcriptional regulation of key genes, particularly the F3'5'H and F3'H genes, in the anthocyanin biosynthesis pathway. By integrating existing knowledge, the development of this high-quality reference genome for S. americanum will facilitate the identification and utilization of novel abiotic and biotic stress-resistance genes for improvement of Solanaceae and other crops.

APETALA2 is involved in ABA signaling during seed germination.

APETALA2 (AP2) is well known for regulating the development of floral organs, ovules, seed coats, and the mass of seeds, but the role of AP2 in seed germination remains unclear. Here, we report that AP2 interacts with ABI5 in nuclear speckles and functions in controlling seed germination. Genetic study showed that the abi5 mutation could restore the ABA-sensitive phenotype of ap2 mutants, supporting that AP2 antagonizes ABI5 in ABA signaling and ABA-mediated inhibition of seed germination. In addition, we observed the interactions of AP2 with SnRK2.2, SnRK2.3, and SnRK2.6 in nuclear speckles, suggesting that AP2 plays a multifaceted role in the ABA signaling pathway. Our findings revealed that the interactions of AP2 with SnRK2s and ABI5 are critical for ABA signaling in control of seed germination.

Natural variation in SlSOS2 promoter hinders salt resistance during tomato domestication.

Increasing soil salinization seriously impairs plant growth and development, resulting in crop loss. The Salt-Overly-Sensitive (SOS) pathway is indispensable to the mitigation of Na + toxicity in plants under high salinity. However, whether natural variations of SOS2 contribute to salt tolerance has not been reported. Here a natural variation in the SlSOS2 promoter region was identified to be associated with root Na+/K+ ratio and the loss of salt resistance during tomato domestication. This natural variation contains an ABI4-binding cis-element and plays an important role in the repression of SlSOS2 expression. Genetic evidence revealed that SlSOS2 mutations increase root Na+/K+ ratio under salt stress conditions and thus attenuate salt resistance in tomato. Together, our findings uncovered a critical but previously unknown natural variation of SOS2 in salt resistance, which provides valuable natural resources for genetic breeding for salt resistance in cultivated tomatoes and other crops.

Identification, molecular characterization and expression of JAZ genes in Lycoris aurea.

Jasmonates (JAs) are key phytohormones involved in regulation of plant growth and development, stress responses, and secondary metabolism. It has been reported that treatments with JAs could increase the contents of Amaryllidaceae alkaloids in Amaryllidaceae plants. Jasmonate ZIM (zinc-finger inflorescence meristem) domain (JAZ) proteins are key components in JA signal processes. However, JAZ proteins have not been characterized in genus Lycoris. In this study, we identified and cloned seven differentially expressed JAZ genes (namely LaJAZ1-LaJAZ7) from Lycoris aurea. Bioinformatic analyses revealed that these seven LaJAZ proteins contain the ZIM domain and JA-associated (Jas, also named CCT_2) motif. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis revealed that these LaJAZ genes display different expression patterns in L. aurea tissues, and most of them are inducible when treated with methyl jasmonate (MeJA) treatment. Subcellular localization assay demonstrated that LaJAZ proteins are localized in the cell nucleus or cytoplasm. In addition, LaJAZ proteins could interact with each other to form homodimer and/or heterodimer. The findings in this study may facilitate further functional research of the LaJAZ genes, especially the potential regulatory mechanism of plant secondary metabolites including Amaryllidaceae alkaloids in L. aurea.

GTX.Digest.VCF: an online NGS data interpretation system based on intelligent gene ranking and large-scale text mining.

BACKGROUND: An important task in the interpretation of sequencing data is to highlight pathogenic genes (or detrimental variants) in the field of Mendelian diseases. It is still challenging despite the recent rapid development of genomics and bioinformatics. A typical interpretation workflow includes annotation, filtration, manual inspection and literature review. Those steps are time-consuming and error-prone in the absence of systematic support. Therefore, we developed GTX.Digest.VCF, an online DNA sequencing interpretation system, which prioritizes genes and variants for novel disease-gene relation discovery and integrates text mining results to provide literature evidence for the discovery. Its phenotype-driven ranking and biological data mining approach significantly speed up the whole interpretation process. RESULTS: The GTX.Digest.VCF system is freely available as a web portal at http://vcf.gtxlab.com for academic research. Evaluation on the DDD project dataset demonstrates an accuracy of 77% (235 out of 305 cases) for top-50 genes and an accuracy of 41.6% (127 out of 305 cases) for top-5 genes. CONCLUSIONS: GTX.Digest.VCF provides an intelligent web portal for genomics data interpretation via the integration of bioinformatics tools, distributed parallel computing, biomedical text mining. It can facilitate the application of genomic analytics in clinical research and practices.